Bad service and only feedback is threats

Two months after renewal of contract to lower packadge( was not using half of airtime and data of old contract) airtime was depleted even after transfer of allot of airtime from old contract. a month later found out my contract that I picked out of MTN booklet failed and I had no data on contract. Then \corected". then suddenly massive deduction from bank account. Never received itemeised billing that was charged so no record of usage. Been to 5 shops"